State-owned Russian oil firm Rosneft has posted another leap in profits after buying the key production assets of troubled rival Yukos.

Oil from the huge Yuganskneftegaz fields helped push Rosneft's net profit to $3.7bn (£2.1bn) for the first nine months of 2005, up from $620m in 2004.

Sales of oil and gas in the period rose from $1.9bn to $11.5bn.

Rosneft bought Yugansk in 2004 after its was seized from Yukos to settle an unpaid tax bill.

The deal more than doubled Rosneft's oil reserves and rocketed it from a small state-owned company into one of Russia's top three oil firms.

Russia is now planning a partial privatisation of Rosneft, with shares going on sale later this year.

Tighter controls

Rosneft snapped up Yukos's main production unit Yuganskneftegaz in a forced auction in December 2004.

It followed government demands that Yukos pay off a huge back taxes bill.

The affair also led to the arrest and imprisonment of company founder Mikhail Khodorkovsky.

It also brought widespread criticism that the company's problems were politically motivated as well as bringing international attention onto Russia and how it treats investors and stock market listed companies.

The Yuganskneftegaz field has estimated reserves of 1.6bn tonnes of oil.

The move was seen by some as part of a wider plan to bring more of Russia's valuable natural resources under state-control at a time when commodity prices are reaching record levels.

A merger between Rosneft and the majority state-owned gas monopoly Gazprom was abandoned last year.